internal/lsp/cache: fix a staticcheck warning by handling error

Change-Id: Ic8d1e7a046d60eb98007e355f3bef2537072a473
Reviewed-on: https://go-review.googlesource.com/c/tools/+/271298
Trust: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
diff --git a/internal/lsp/cache/imports.go b/internal/lsp/cache/imports.go
index b910aac..524d581 100644
--- a/internal/lsp/cache/imports.go
+++ b/internal/lsp/cache/imports.go
@@ -136,6 +136,9 @@
 	_, inv, cleanupInvocation, err := snapshot.goCommandInvocation(ctx, source.LoadWorkspace, &gocommand.Invocation{
 		WorkingDir: snapshot.view.rootURI.Filename(),
 	})
+	if err != nil {
+		return nil, err
+	}
 	pe.WorkingDir = inv.WorkingDir
 	pe.BuildFlags = inv.BuildFlags
 	pe.WorkingDir = inv.WorkingDir